Droop improvement in high current range on PSS-LEDs

The droop property of blue GaN light emitting diodes (LEDs) has been improved by creating a 9 quantum well (QW) LED on a patterned sapphire substrate (PSS). The droop ratio was improved from 45.9 to 7.6%. At a wavelength of 447 nm, and with standard on-header packaging, the 9QW PSS-LED had an output power of 27.6 mW and an EQE of 49.7% at a current of 20 mA. The output power of the 9QW PSS-LED remains linear with increasing drive current, even up to relatively high current density, and the EQE is almost constant.